Here is a simple script to test for reallocated sector count and report through mail if it finds any.
Reallocated sectors means your disk has sectors where it can’t read/write thus it uses a reserved space to reallocate those sectors.
In general reallocated sectors are bad news for your disk and you should consider a backup and send to warranty.
The script reads the smart value and reports. It should be self explanatory to use it just type ./scriptname.sh nameofthehost. Afterwards set a cron to run daily.
Credits to Thorsten Rhau for the base script.